Nanoparticle Synthesis in Ionic Liquids

Ionic liquids are able to offer outstanding properties as media for the synthesis of nanoparticles. The low surface tension of many ionic liquids leads to high nucleation rates and, in consequence, to small particles. The ionic liquid itself can act as an electronic as well as a steric stabiliser and depress particle growth. As highly structured liquids, ionic liquids have a strong effect on the morphology of the particles formed. Three synthetic techniques make special use of the unique properties that ionic liquids offer when compared to conventional VOCs (volatile organic solvents). Firstly, direct microwave synthesis can be used because of the ionic character and high polarisability of the synthetic medium. Secondly, physical vapour depostion (PVD) under high vacuum becomes possible due to the low vapour pressure of some ionic liquids. In order to make full use of the possibilities that ionic liquids offer we have designed a set of reducing ionic liquids which can be used as direct reaction partners for the generation of metal nanoparticles. Thirdly, sonochemistry has proven an especially powerful route towards oxidic nanomaterials.